Mike,
Yes, you can do it and it will turn out just fine. I did along with my son about 6 or so years ago on our previous coach a '99 Fleetwood Bounder 34V. About 99.9% of the white had just deteriorated away and the roof was almost all black. Talk about some serious added heat, WOW!!!
Yes, we did the Dicor two part system. It was a hot, very intensive day for the two of us. First, wash with soap and water, very aggressively. Then, apply the primer/prep solution they recommend. Then, when that's dry, apply your first coat of roof coating. Let that dry as long as possible and hit it with your second coat.
We sold our Bounder to our Daughter and Son in law and to this day, it still looks as good as when the coach was new. As stated, a long, hard, intense day but, it was done and will last for years. Good luck. Here's a pic of the after effect. I sure wish I'd have taken one of the before so you could see the massive difference.
Scott
